The present invention relates to edible fat blends suitable for preparing edible fat products, such as margarines, and in its preferred aspects, to stick and tub margarines prepared from sunflower oil.
Sunflower oil is high in polyunsaturates, principally linoleic acid, and relatively low in saturated fatty acids. The art has therefore endeavored to prepare margarine from it. However, the preparation of margarine from liquid oils such as sunflower oil is a complex matter.
Margarines for home table use have been produced by preparing partially hydrogenated liquid oils or blends of liquid vegetable oils with hydrogenated hardstock and emulsifying the blends with suitable aqueous phase compositions to prepare a water-in-oil emulsion. The amount and character of the hardstock have been varied depending on the consistency of product desired. To be acceptable, a margarine product must have certain flow characteristics while resisting free oil separation and yet should rapidly melt on the tongue. In the past, when it was attempted to prepare margarine based entirely on sunflower oil by blending liquid oil with a hydrogenated hardstock, the quality of the margarine diminished with time as fat recrystallization or graininess set in, resulting in a sandy texture.
The texture problem of sunflower oil margarines was discussed by Freier et al in Industria Alimentara, Vol. 24, no. 11, November 1973, at pages 604-607. The title of the Freier et al article translates to "The Transesterification of the Sunflower Seed oil--A Method for Improving the Quality of Margarine". According to the authors, margarines made exclusively of sunflower oil undergo polymorphic changes and recrystallizations in the oil phase which modify the textural properties of the margarine. Some samples become "floury" after 10 days and "sandy" after 20 days when subjected to temperature cycling. However, where from 40 to 50% of the oil phase of the margarines were transesterified binary or ternary mixtures of liquid and hydrogenated sunflower oils, the sandy texture was not noticed for periods of 30 days or more. These margarines had linoleic acid contents up to about 36% as measured by gas chromatography. The successful margarine products (samples M-3, 4, 7 and 8) also contained a non-transesterified portion, half of which was hydrogenated sunflower oil.
The problem of recrystallization was earlier identified by Gander et al in Belgian Pat. No. 670,371. Also related to this disclosure are DAS (Deutsches Ausgelegeschrift) No. 1,299,992 and Netherlands Pat. No. 149,686. In the Belgian patent, Gander et al disclose that margarines based on blends of hydrogenated and unhydrogenated sunflower seed oil, undergo recrystallization of the solid fat to the stable beta-modification. The resulting margarine is said to become hard and crisp on one hand, and gritty and mealy on the other. During melting in the mouth, an unpleasant sensation is caused. Example 2 of this patent shows a margarine prepared with a blend of 40% liquid sunflower oil, 40% sunflower oil hydrogenated to a melting point of 33.degree. C., and 20% sunflower oil hydrogenated to 42.degree. C. This product was unsuccessful in terms of texture. The patent also shows in Example 4 that a margarine prepared with an interesterified blend of sunflower oils, 40% liquid and 60% hydrogenated to 33.degree. C., is too soft. Successful margarines having 25.2% linoleic and 20.5% linoleic acid were prepared from blends which contained 80% of a transesterified mixture of liquid and hydrogenated sunflower oil and 20% of either all-liquid or liquid-plus-hydrogenated sunflower oils.
A later disclosure, found in U.S. Pat. Nos. 3,748,348 and 3,859,447, to Sreenivasan, states that directed interesterification can be employed to prepare a sunflower oil margarine without any hydrogenation. However, the directed process requires the use of an aprotic solvent and takes several days to complete. Other recent disclosures, such as U.S. Pat. No. 3,855,254 to Haighton et al, indicate that the directed interesterification of sunflower oil can be more rapidly carried out; however, the cycling of the temperature at 1.degree. to 15.degree. C. below the cloud point requires considerable care, investment in equipment, and energy.